i have my gm for over a year and my pm about 6 months. i don't use them exclusively either.How long have you had them?
i can tell you that i am not careful with them. the gm has been packed full and used as a carry on for car trips. the pm has been on the floor and in the grass.
for me the mail selling point is not whether or not they are indestructible it is that they are so light weight and really fun.